Paper and textile materials made entirely of natural fibers (e.g., animal or vegetable fibers) and/or cellulosic fibers (e.g., pulp fibers) are frequently recycled. Techniques to recycle these materials have been developed to break them down into fibers or fiber-like material and then reform the materials to provide paper and paper-like products. Natural fiber textiles and/or paper are dispersed in water by a pulping operation to create a slurry of individual fibers. The fibers may be cleaned and or treated to remove ink, adhesives or other contaminants. The treated fibers may be further refined and/or fractionated before being formed into a wet-laid web. In conventional recycling operations, synthetic materials are considered contaminants and are typically removed. The synthetic material may be present in the form of synthetic or manufactured fibers and/or filaments or in the form of adhesives, binders or the like.
Woven and nonwoven fabrics composed partially or entirely of synthetic or manufactured fibers have generated problems for conventional processes focused on recycling natural and/or cellulosic fibers. In addition, high-strength natural and/or cellulosic fiber based fabrics that utilize adhesives, binders and/or mechanical entangling, such as hydraulic entangling, also provide problems for conventional recycling processes.
These types of fabrics are generally difficult or impossible to disperse into individual fibers in a wet process such as a pulping operation. This is particularly apparent if the fabric is formed of synthetic fibers joined by thermal or adhesive bonding. In some cases, fiber or filament “ropes” may form. If the synthetic material is thermoplastic, mechanical work from the processes used to break-up or shred the material may generate sufficient heat to cause the material to melt into unusable globs and clumps.
Generally speaking, fabrics composed of synthetic materials or composites containing synthetic and natural materials are recycled utilizing one of two methods. In the first method, fabrics composed entirely of synthetic thermoplastic material are cleaned, melted and then extruded or formed into staple fibers, continuous filaments or films. If the fabric is a composite containing synthetic thermoplastic materials and natural (or non-thermoplastic synthetic material), the natural (or non-thermoplastic synthetic) materials must first be separated from the thermoplastic materials before further processing. This is often impractical because thermal, mechanical and/or adhesive bonding between the components of the composite make separation difficult. Even if separation is possible, the method requires multiple processing steps and energy to melt and reform the material. While the resulting fibers, filaments or films may contain recycled materials, the fibers, filaments or films may be characterized as “manufactured” or “extruded” from recycled polymer feedstock.
The second method involves mechanically breaking up a fabric into smaller pieces such as fiber bundles, threads and/or individual fibers. This is normally accomplished by mechanical tearing and shredding dry material. For example, International Application PCT/SE95/00938 states that it is known to mechanically shred dry nonwoven and textile waste and that dry mixed waste containing both synthetic and natural fibers may be used. According to PCT/SE95/00938, a significant feature of shredding and tearing techniques is that the tearing or shredding operation is often incomplete so that recycled fibers are present partly in the form of discrete bits of the original fabric that may be characterized as “flocks” or fiber bundles. These flocks are described as providing non-uniformities that give webs containing such flocks a textile-like appearance.
Flocks and bits of fabric are difficult to process in subsequent operations such as, for example, a wet-laying process, air-laying process, hydraulic entangling process or other web-forming processes. Presence of these non-uniformities may reduce the value of the recycled fibers as well as degrade the appearance, strength, uniformity and other desirable properties of a web or fabric made with the recycled fibers. Removing the non-uniformities by screening or other techniques reduces the efficiency of the fiber recovery. Additional dry mechanical chopping, shredding, tearing, garnetting or picking operations to reduce the fiber bundles or flocks into fibers or fiber-like material having a length of less than 5 millimeters may be impractical. In addition, the additional mechanical work may transfer so much energy in the form of heat that the dry material may melt into unusable clumps and may diminish or eliminate any environmental or economic advantages initially presented by recycling the material.
While previous techniques may be of interest to those seeking to recycle thermoplastic material into polymer feedstock for reprocessing as well as those seeking to mechanically tear or shred dry waste fabrics into smaller pieces, they fail to address many existing needs. For example, previous techniques fail to address the need for a wet process to substantially isolate or individualize fibers and/or filaments from a textile or nonwoven fabric. As another example, previous techniques fail to address the need for a wet process to produce usable fibers and fiber-like material from thermally bonded, adhesively bonded and/or mechanically entangled fabrics such as textiles and nonwoven webs.
Previous techniques fail to address the need for a wet process to convert fabrics into individualized fibers and/or filaments having dimensions similar to cellulosic pulps and short natural fibers such as, for example, lengths less than five millimeters. For example, previous techniques fail to address the need for a process to convert fabrics into individualized fibers and/or filaments having dimensions similar to conventional cellulosic pulps and short natural fibers such as, for example, lengths less than five millimeters.
There is still a need for an inexpensive recycled fiber or fiber-like material that may be easily processed into a uniform sheet or web. For example, there is a need for an inexpensive recycled fiber or fiber-like material that may be processed into a uniform sheet or web utilizing conventional wet-forming or dry-forming techniques. This is also a need for a uniform sheet or web that may include at least a portion of an inexpensive recycled fiber or fiber-like material.
There is also a need for a high strength sheet or wiper that is able to quickly absorb several times its weight in water, aqueous liquid or oil. A need exists for a sheet or wiper that contains an inexpensive recycled fiber or fiber-like material and which is able to quickly absorb several times its weight in water, aqueous liquid or oil. A need exists for a sheet or wiper that contains an inexpensive recycled fiber or fiber-like material and that can be used as a wiper or as a fluid distribution layer and/or absorbent component of an absorbent product. Meeting this need is important since it is both economically and environmentally desirable to substitute recycled fiber or fiber-like materials for high-quality virgin wood fiber pulp and/or new synthetic fibers or filaments and still provide a product that can be used as a wiper or as a fluid distribution layer and/or absorbent component of an absorbent product.